This invention relates to slide fasteners, more paticularly to a slider-operated fastener of the concealed or masked type which in its closed disposition substantially simulates a garment seam.
Slide fasteners are well known which comprise a pair of rows of interlocking fastener elements formed from a continuous filament or wire and secured to respective folded edges of opposed stringer tapes, and such fasteners when closed by the slider mask the elements from external view, only leaving a linear seam in the junction of the opposed tapes.
In such known concealed or masked type of fastener, there were used support tapes of a warp-knit structure, as contrasted to conventional woven fabric tapes, for supporting thereon respective rows of fastener elements. The warp-knit tape inherently has a multiplicity of wales and interwale grooves on one or the other or both of its surfaces, which wales and interwale grooves can be conveniently utilized for securing the fastener element firmly to the tape for example by engaging the wales with recesses formed in the elements. While fasteners including stringers of the character described are advantageous from the point of view of attaching the fastener elements securely to the respective support tapes, they have presented a difficulty in sewing the fastener properly into position on a garment fabric or other articles. This difficulty arose from the fact that the portion of the support tape at and along which the fastener was to be sewn to the garment was structurally identical to and as hard and heavy as the remaining portions of the tape, with the wales at the first-mentioned tape portion often interferring with or obstructing the normal thrusting action of the sewing needle.